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Source: American Journal of Physiology. Heart and Circulatory Physiology

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Total 253 results found since Jan 2013.

Letter to the editor: "Targeting cerebrovascular myogenic dysfunction in stroke".
PMID: 24833733 [PubMed - in process]
Source: American Journal of Physiology. Heart and Circulatory Physiology - May 15, 2014 Category: Physiology Authors: Jiménez-Altayó F, Planas AM, Vila E Tags: Am J Physiol Heart Circ Physiol Source Type: research

Mechano-electrical coupling as framework for understanding functional remodeling during LBBB and CRT.
In conclusion, MEC may represent a useful framework for better understanding the long-term changes in cardiac electrophysiology and contraction following LBBB as well as CRT. PMID: 24748591 [PubMed - as supplied by publisher]
Source: American Journal of Physiology. Heart and Circulatory Physiology - April 18, 2014 Category: Physiology Authors: Kuijpers NH, Hermeling E, Lumens J, Eikelder HT, Delhaas T, Prinzen FW Tags: Am J Physiol Heart Circ Physiol Source Type: research

Adaptive Right Ventricular Performance in Response to Increased Afterload in a Lamb Model of Congenital Heart Disease: Evidence for Enhanced Anrep Effect.
Abstract Patients with pulmonary hypertension associated with congenital heart disease survive longer with preserved right ventricular (RV) function compared to those with primary pulmonary hypertension. The purpose of this study was to test the hypothesis that superior RV performance can be demonstrated, at baseline and when challenged with increased RV afterload, in lambs with chronic left-to-right cardiac shunts compared to control lambs. A shunt was placed between the pulmonary artery and the aorta in fetal lambs (shunt). RV pressure volume loops were obtained 4 weeks after delivery in shunt and control lambs,...
Source: American Journal of Physiology. Heart and Circulatory Physiology - February 21, 2014 Category: Physiology Authors: Johnson RC, Datar SA, Oishi PE, Bennett SH, Maki J, Sun CE, Johengen MJ, He Y, Raff GW, Redington AN, Fineman JR Tags: Am J Physiol Heart Circ Physiol Source Type: research

Role of Aromatase in Sex-Specific Cerebrovascular Endothelial Function in Mice.
Abstract Stroke risk and outcome are strongly modified by estrogen. In addition to ovaries, estrogen is produced locally in peripheral tissue by the enzyme aromatase, and extra-gonadal synthesis becomes the major source of estrogen after menopause. Aromatase gene deletion in female mice exacerbates ischemic brain damage after stroke. However, it is not clear which cell type is responsible for this effect, since aromatase is expressed in multiple cell types, including cerebrovascular endothelium. We tested the hypothesis that cerebrovascular aromatase contributes to sex differences in cerebrovascular endothelial fu...
Source: American Journal of Physiology. Heart and Circulatory Physiology - February 7, 2014 Category: Physiology Authors: Zuloaga KL, Davis CM, Zhang W, Alkayed NJ Tags: Am J Physiol Heart Circ Physiol Source Type: research

Interaction between respiration and right versus left ventricular volumes at rest and during exercise - a real-time cardiac magnetic resonance study.
Conclusion: Ventricular volumes oscillate with respiratory phase such that RV and LV volumes are maximal at peak inspiration and expiration, respectively. Thus, interpretation of RV versus LV volumes requires careful definition of the exact respiratory time point for proper interpretation, both at rest and during exercise. PMID: 24464754 [PubMed - as supplied by publisher]
Source: American Journal of Physiology. Heart and Circulatory Physiology - January 24, 2014 Category: Physiology Authors: Claessen G, Claus P, Delcroix M, Bogaert J, La Gerche A, Heidbuchel H Tags: Am J Physiol Heart Circ Physiol Source Type: research

The relationship between longitudinal, lateral and septal contribution to stroke volume in patients with pulmonary regurgitation and healthy volunteers.
Discussion: PR-patients have decreased longitudinal contribution to RVSV and increased lateral pumping, resulting in larger outer volume changes and septal motion towards the RV. The changes in RV pumping physiology in PR-patients may be explained by RV remodelling resulting in lower systolic inflow of blood into the right atrium in relation to SV. This reduces pendulum volume between caval veins and right atrium. Decreased dependence of atrioventricular plane motion to right ventricular stroke volume suggests that the tricuspid annular excursion (TAPSE), as a marker of RV function, is less valid in these patients. PM...
Source: American Journal of Physiology. Heart and Circulatory Physiology - January 17, 2014 Category: Physiology Authors: Stephensen SS, Steding-Ehrenborg K, Munkhammar P, Heiberg E, Arheden H, Carlsson M Tags: Am J Physiol Heart Circ Physiol Source Type: research

Beneficial effects of acute inhibition of the oxidative pentose phosphate pathway in the failing heart.
Abstract In vitro studies suggested that glucose metabolism through the oxidative pentose phosphate pathway (oxPPP) can paradoxically feed superoxide-generating enzymes in failing hearts. We therefore tested the hypothesis that acute inhibition of the oxPPP reduces oxidative stress and enhances function and metabolism of the failing heart, in vivo. In 10 chronically instrumented dogs, congestive heart failure (HF) was induced by high-frequency cardiac pacing. Myocardial glucose consumption was enhanced by raising arterial glycemia to levels mimicking post-prandial peaks, before and after intravenous administration...
Source: American Journal of Physiology. Heart and Circulatory Physiology - January 10, 2014 Category: Physiology Authors: Vimercati C, Qanud K, Mitacchione G, Sosnowska D, Ungvari ZI, Sarnari R, Mania D, Patel N, Hintze TH, Gupte SA, Stanley WC, Recchia FA Tags: Am J Physiol Heart Circ Physiol Source Type: research

Cardiac Function of the Naked Mole-rat: Ecophysiological Responses to Working Underground.
Abstract The naked mole-rat (NMR) is a strictly subterranean rodent with a low resting metabolic rate. Nevertheless, it can greatly increase its metabolic activity to meet the high energetic demands associated with digging through compacted soils in its xeric natural habitat where food is patchily distributed. We hypothesized that the NMR heart would naturally have low basal function and exhibit a large cardiac reserve, thereby mirroring the species' low basal metabolism and large metabolic scope. Echocardiography showed that young (2-4 year old) healthy NMRs have low fractional shortening (28 ± 2%), ejection fra...
Source: American Journal of Physiology. Heart and Circulatory Physiology - December 20, 2013 Category: Physiology Authors: Grimes KM, Voorhees A, Chiao YA, Han HC, Lindsey ML, Buffenstein R Tags: Am J Physiol Heart Circ Physiol Source Type: research

Left ventricular energetics: New insight into the plasticity of regional contributions at rest and during exercise.
In conclusion, the present findings provide unique insight into human LV function by demonstrating that within this functional syncytium, significant differences in the regional contributions of kinetic energy to overall LV work exist. Importantly, regional contributions are not fixed but highly plastic and the underpinning LV wall energetics adjust according to the prevailing cardiovascular demand. PMID: 24213618 [PubMed - as supplied by publisher]
Source: American Journal of Physiology. Heart and Circulatory Physiology - November 8, 2013 Category: Physiology Authors: Stöhr EJ, Gonzalez-Alonso J, Bezodis IN, Shave RE Tags: Am J Physiol Heart Circ Physiol Source Type: research

A novel approach to assess hemorrhagic shock severity using the arterially-determined left ventricular isovolumic contraction period.
In conclusion, ventilation-induced preload variation principally affects the arterially determined isovolumic contraction period (AIC). Moreover, AIC can be determined solely from the arterial pressure waveform, whereas PEP also requires ECG measurement. Importantly, AIC determined from either the carotid or aortic pressure waveform are interchangeable suggesting that, in contrast to PEP, AIC may be site independent. PMID: 24124184 [PubMed - as supplied by publisher]
Source: American Journal of Physiology. Heart and Circulatory Physiology - October 11, 2013 Category: Physiology Authors: van Houwelingen MJ, Merkus D, Hofland J, Bakker J, Tenbrinck R, Te Lintel Hekkert M, van Dijk G, Hoeks AP, Duncker DJ Tags: Am J Physiol Heart Circ Physiol Source Type: research

Protein Nitration Impairs Myogenic Tone of Rat Middle Cerebral Arteries in Both Ischemic and Nonischemic Hemispheres after Ischemic Stroke.
Conclusion: Ischemia/reperfusion injury impairs vessel reactivity in both hemispheres via nitration. We suggest that sham animals rather than nonischemic side should be used as a control in preclinical stroke studies. PMID: 24097431 [PubMed - as supplied by publisher]
Source: American Journal of Physiology. Heart and Circulatory Physiology - October 4, 2013 Category: Physiology Authors: Coucha M, Li W, Johnson M, Fagan SC, Ergul A Tags: Am J Physiol Heart Circ Physiol Source Type: research

Role of 20-HETE,TRP channels & BKCa in dysregulation of pressure-induced Ca2+ signaling and myogenic constriction of cerebral arteries in aged hypertensive mice.
Role of 20-HETE,TRP channels & BKCa in dysregulation of pressure-induced Ca2+ signaling and myogenic constriction of cerebral arteries in aged hypertensive mice. Am J Physiol Heart Circ Physiol. 2013 Oct 4; Authors: Toth P, Csiszar A, Tucsek Z, Sosnowska D, Gautam T, Koller A, Laniado Schwartzman M, Sonntag WE, Ungvari ZI Abstract Hypertension in the elderly substantially increases the risk stroke and vascular cognitive impairment (VCI) in part due to an impaired functional adaptation of aged cerebral arteries to high blood pressure. To elucidate the mechanisms underlying impaired autoregulatory protec...
Source: American Journal of Physiology. Heart and Circulatory Physiology - October 4, 2013 Category: Physiology Authors: Toth P, Csiszar A, Tucsek Z, Sosnowska D, Gautam T, Koller A, Laniado Schwartzman M, Sonntag WE, Ungvari ZI Tags: Am J Physiol Heart Circ Physiol Source Type: research

Soluble Epoxide Hydrolase Inhibitor trans-4-4-(3-Adamantan-1-yl-ureido)-cyclohexyloxy-benzoic Acid (t-AUCB) is Neuroprotective in Rat Model of Ischemic Stroke.
Conclusions: These findings suggest that t-AUCB may exert its neuroprotective effects by affecting multiple components of neurovascular unit including neurons, astrocytes and microvascular flow. PMID: 24043255 [PubMed - as supplied by publisher]
Source: American Journal of Physiology. Heart and Circulatory Physiology - September 16, 2013 Category: Physiology Authors: Shaik JS, Ahmad M, Li W, Rose ME, Foley LM, Hitchens KT, Graham SH, Hwang SH, Hammock BD, Poloyac SM Tags: Am J Physiol Heart Circ Physiol Source Type: research

Attenuated muscle metaboreflex-induced increases in cardiac function in hypertension.
Abstract Sympatho-activation may be excessive during exercise in subjects with hypertension leading to increased susceptibility to adverse cardiovascular events including arrhythmias, infarction, stroke, and sudden cardiac death. The muscle metaboreflex is a powerful cardiovascular reflex capable of eliciting marked increases in sympathetic activity during exercise. We investigated the effects of hypertension on the mechanisms of the muscle metaboreflex using conscious, chronically instrumented dogs trained to run on a motor-driven treadmill. Experiments were performed before and 30.9 ± 4.2 days after induction o...
Source: American Journal of Physiology. Heart and Circulatory Physiology - September 6, 2013 Category: Physiology Authors: Sala-Mercado JA, Spranger MD, Abu-Hamdah R, Kaur J, Coutsos M, Stayer D, Augustyniak RA, O'Leary DS Tags: Am J Physiol Heart Circ Physiol Source Type: research

Effects of acute vasodilation on the hemodynamic response to muscle metaboreflex.
Abstract The aim of the present study was to test the contribution of stroke volume in hemodynamic response to muscle metaboreflex activation in healthy individuals. We hypothesized that an acute decrease in cardiac after-load and pre-load due to the administration of a vasodilating agent could reduce post-exercise muscle ischemia (PEMI)-induced stroke volume (SV) response. Ten healthy males (age 33.6±1.3 years) were enrolled and randomly assigned to the following study protocol: 1) PEMI session, 2) control exercise recovery (CER) session, 3) PEMI after sublingual administration of 5 mg of isosorbide dinitrate (I...
Source: American Journal of Physiology. Heart and Circulatory Physiology - August 30, 2013 Category: Physiology Authors: Marongiu E, Piepoli M, Milia R, Angius L, Pinna M, Bassareo P, Roberto S, Tocco F, Concu A, Crisafulli A Tags: Am J Physiol Heart Circ Physiol Source Type: research